arXiv subjects

Konstantin Iakoubovskii

Publications and source records attributed to Konstantin Iakoubovskii.

3 recordsLinked to original sources

arXiv2026

HPHT growth of centimeter-sized cubic boron nitride crystals

Single crystals of cubic boron nitride (cBN) exceeding 10 mm in size were grown by the high-pressure high-temperature (HPHT) temperature-gradient method using a Ni-Cr-based solvent catalyst. Compared with the previously reported maximum crystal size of approximately 3 mm, this improvement was achieved by maintaining a stable precursor flux during one week of growth at a source temperature of 1950 °C. In contrast to diamonds, which were grown with the same HPHT cell and showed nearly isometric shapes, the cBN crystals had elongated shapes. We attribute this cBN morphology to a localized growth near the BN source due to the relatively low effective diffusivity of boron and nitrogen species in the metallic solvent.

cond-mat.mtrl-sci↗

arXiv2026

Detection of acoustic phonons in carbon by Raman spectroscopy

We detected acoustic phonons in graphite and diamond by Raman spectroscopy supported by density functional theory calculations. The activation of these normally forbidden Raman modes was achieved via lattice amorphization in case of graphite and by boron doping in case of diamond. The doping-induced Raman signal in diamond was identified with substitutional boron of tetrahedral symmetry via its dependences on excitation wavelength and polarization. Comparison of the Raman spectra of amorphized graphite and heavily boron-doped diamond suggests the emergence of graphitic-like disorder in the diamond lattice. The reported approach is not limited to carbon and can be extended to a wide range of other materials.

cond-mat.mtrl-sci↗

arXiv2026

Optical centers in cubic boron nitride and diamond: remarkable similarities

We present a comparative study of optical absorption and luminescence from cubic boron nitride (cBN) and diamond grown by the high-pressure high-temperature technique in the same cubic press. We note remarkable similarities in spectral and spatial dependences for these two materials. Using the previous identification of defects in diamond, we tentatively assign the optical center responsible for yellow color in some cBN crystals to substitutional oxygen at the nitrogen site, the RC1 and RC3 centers to a defect comprising substitutional oxygen and a boron vacancy in the neutral and negative charge states, respectively, the GC1 center to a nickel-related defect, the 1.816 eV (683 nm) luminescence peak to a Si-vacancy complex, and the BN1 center to an interstitial-related defect.

cond-mat.mtrl-sci↗